Ultrasonic surgical instruments are known which include an ultrasonic surgical shears having an ultrasonic surgical blade, a clamping arm operable to open and close toward the blade, and a polytetrafluoroethylene tissue pad which is attached to the clamping arm and which includes a clamping surface. The clamping arm exerts a clamping force on a blood vessel which is positioned between the clamping surface of the tissue pad and the blade. The result of the ultrasonically-vibrating ultrasonic surgical blade and the clamping force on the blood vessel is a coaptation of the blood vessel (a bringing together of the walls of the blood vessel), a transection (a cutting) of the coapted blood vessel, and a coagulation (a sealing) of the coapted cut ends of the blood vessel. At the completion of a tissue transection, the ultrasonically-vibrating ultrasonic surgical blade contacts and cuts away some of the polytetrafluoroethylene tissue pad because of the frictional abrasion and frictional heat generated by the blade vibrating against the tissue pad. Exemplary devices are described in U.S. Pat. Nos. 5,322,055 and 6,325,811, the contents of which are incorporated herein by reference.
Still, scientists and engineers continue to seek improved ultrasonic surgical shears and improved tissue pads for ultrasonic surgical shears.